C12/15 vs C16/20

C16/20 is 1.1 times as stiff as C12/15. Their densities are about the same. Per unit mass C16/20 is 1.1 times as stiff. Strength: f_ck = 12 MPa for C12/15, f_ck = 16 MPa for C16/20.

C12/15 EN 1992-1-1 C16/20 EN 1992-1-1

Side by side

ratio = C16/20 / C12/15 · log scale

Property	C12/15	C16/20	Unit	Ratio
E Young's modulus	27	29	GPa	1.07×
G Shear modulus	11.25	12.08	GPa	1.07×
ν Poisson's ratio	0.2	0.2	–	1×
ρ Density	2447	2447	kg/m³	1×
γ Weight density	24	24	kN/m³	1×
α Coefficient of thermal expansion	10	10	10⁻⁶/K	1×
f_ck Characteristic cylinder strength	12	16	MPa	1.33×
f_ck,cube Characteristic cube strength	15	20	MPa	1.33×
f_cm Mean cylinder strength	20	24	MPa	1.2×
f_ctm Mean tensile strength	1.6	1.9	MPa	1.19×
f_ctk,0.05 Tensile strength, 5 % fractile	1.1	1.3	MPa	1.18×
f_ctk,0.95 Tensile strength, 95 % fractile	2	2.5	MPa	1.25×
ε_c1 Strain at peak stress	1.8	1.9	‰	1.06×
ε_cu1 Ultimate strain	3.5	3.5	‰	1×
ε_c2 Strain at peak, parabola–rectangle	2	2	‰	1×
ε_cu2 Ultimate strain, parabola–rectangle	3.5	3.5	‰	1×
n Exponent, parabola–rectangle	2	2	–	1×
ε_c3 Strain at peak, bilinear	1.75	1.75	‰	1×
ε_cu3 Ultimate strain, bilinear	3.5	3.5	‰	1×
E/ρ Specific stiffness E/ρ · derived	11.03	11.85	MJ/kg	1.07×
c₀ Bar wave speed √(E/ρ) · derived	3322	3442	m/s	1.04×
f/ρ Specific strength f/ρ · derived	4.903	6.538	kJ/kg	1.33×

Values at the first thickness band or product form of each material (EN 1992-1-1; EN 1992-1-1). A minimum and a characteristic value are not the same kind of number — read the ratio as a guide. Each material's page lists every band and every source.